Definitely possible.
Look at Hierarchical Sheets in help. On Mac Cmd-H, 2nd from bottom left tool opens up the hierarchy navigator. "S" let's your add sheets to the top level sheet. (the toolbar item is what looks to me like a transistor with a red + on it, on the right).
I haven't used this well, but you place references to the sheets on the top level, and you add Sheet Pins to interconnect.
This for sure, use hierarchical sheets -- they're super handy for keeping logical components separate. In my
template, I have
a second sheet under the first empty sheet that starts out with the jacks and power and all of that stuff. I've also found it
really helpful when designing something big - like when doing a chorus pedal I'll usually put the LFO section on its own sheet.
Recently I did the L5 preamp and put each channel, the multifilter, the distortion, and the compressor all on different sheets.
One way that they're really powerful is that there's a feature called 'multi-channel'. If you have a 'channel' on a sheet
and an identical one on another sheet, you can actually do the layout for one of the channels, and then you can magically
force all of the other duplicate channels to have an identical layout without having to move crap around. This can be
handy for things with repeated sections like phasers. I used it while prototyping a 9V isolated supply, where each
of the isolated 9V supply rails had an identical layout and then I just kind of tetris'ed them around to fit.
However, if what you're really looking for is a way to have multiple _boards_ in one schematic (e.g. a top board and a bottom board),
unfortunately I don't think KiCad supports that right now. I really wish it were more flexible in this way. It'd be really handy for
designing multi-board effects to link multiple schematics and boards together in one project.
I'd also really love the ability to create multiple PCBs from a single schematic (which you can kind of do with copying
and version control, I guess, but it's not native). I'd want to do this to make it easy to design both a through-hole and a
SMD version of a board.
Also, you can KIND OF hack this by opening the .kicad_pcb and .kicad_sch files individually (not using the project manager)
which will launch the standalone apps. So that at least lets you have two schematic windows or two PCB windows open.
I ended up doing this on the L5 project I talked about, because it required a custom double-footswitch board.
